drivers/md/dm-region-hash.c

   1 /*
   2  * Copyright (C) 2003 Sistina Software Limited.
   3  * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include <linux/dm-dirty-log.h>
   9 #include <linux/dm-region-hash.h>
  10
  11 #include <linux/ctype.h>
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/vmalloc.h>
  15
  16 #include "dm.h"
  17
  18 #define DM_MSG_PREFIX   "region hash"
  19
  20 /*-----------------------------------------------------------------
  21  * Region hash
  22  *
  23  * The mirror splits itself up into discrete regions.  Each
  24  * region can be in one of three states: clean, dirty,
  25  * nosync.  There is no need to put clean regions in the hash.
  26  *
  27  * In addition to being present in the hash table a region _may_
  28  * be present on one of three lists.
  29  *
  30  *   clean_regions: Regions on this list have no io pending to
  31  *   them, they are in sync, we are no longer interested in them,
  32  *   they are dull.  dm_rh_update_states() will remove them from the
  33  *   hash table.
  34  *
  35  *   quiesced_regions: These regions have been spun down, ready
  36  *   for recovery.  rh_recovery_start() will remove regions from
  37  *   this list and hand them to kmirrord, which will schedule the
  38  *   recovery io with kcopyd.
  39  *
  40  *   recovered_regions: Regions that kcopyd has successfully
  41  *   recovered.  dm_rh_update_states() will now schedule any delayed
  42  *   io, up the recovery_count, and remove the region from the
  43  *   hash.
  44  *
  45  * There are 2 locks:
  46  *   A rw spin lock 'hash_lock' protects just the hash table,
  47  *   this is never held in write mode from interrupt context,
  48  *   which I believe means that we only have to disable irqs when
  49  *   doing a write lock.
  50  *
  51  *   An ordinary spin lock 'region_lock' that protects the three
  52  *   lists in the region_hash, with the 'state', 'list' and
  53  *   'delayed_bios' fields of the regions.  This is used from irq
  54  *   context, so all other uses will have to suspend local irqs.
  55  *---------------------------------------------------------------*/
  56 struct dm_region_hash {
  57         uint32_t region_size;
  58         unsigned region_shift;
  59
  60         /* holds persistent region state */
  61         struct dm_dirty_log *log;
  62
  63         /* hash table */
  64         rwlock_t hash_lock;
  65         mempool_t *region_pool;
  66         unsigned mask;
  67         unsigned nr_buckets;
  68         unsigned prime;
  69         unsigned shift;
  70         struct list_head *buckets;
  71
  72         unsigned max_recovery; /* Max # of regions to recover in parallel */
  73
  74         spinlock_t region_lock;
  75         atomic_t recovery_in_flight;
  76         struct semaphore recovery_count;
  77         struct list_head clean_regions;
  78         struct list_head quiesced_regions;
  79         struct list_head recovered_regions;
  80         struct list_head failed_recovered_regions;
  81
  82         void *context;
  83         sector_t target_begin;
  84
  85         /* Callback function to schedule bios writes */
  86         void (*dispatch_bios)(void *context, struct bio_list *bios);
  87
  88         /* Callback function to wakeup callers worker thread. */
  89         void (*wakeup_workers)(void *context);
  90
  91         /* Callback function to wakeup callers recovery waiters. */
  92         void (*wakeup_all_recovery_waiters)(void *context);
  93 };
  94
  95 struct dm_region {
  96         struct dm_region_hash *rh;      /* FIXME: can we get rid of this ? */
  97         region_t key;
  98         int state;
  99
 100         struct list_head hash_list;
 101         struct list_head list;
 102
 103         atomic_t pending;
 104         struct bio_list delayed_bios;
 105 };
 106
 107 /*
 108  * Conversion fns
 109  */
 110 static region_t dm_rh_sector_to_region(struct dm_region_hash *rh, sector_t sector)
 111 {
 112         return sector >> rh->region_shift;
 113 }
 114
 115 sector_t dm_rh_region_to_sector(struct dm_region_hash *rh, region_t region)
 116 {
 117         return region << rh->region_shift;
 118 }
 119 EXPORT_SYMBOL_GPL(dm_rh_region_to_sector);
 120
 121 region_t dm_rh_bio_to_region(struct dm_region_hash *rh, struct bio *bio)
 122 {
 123         return dm_rh_sector_to_region(rh, bio->bi_sector - rh->target_begin);
 124 }
 125 EXPORT_SYMBOL_GPL(dm_rh_bio_to_region);
 126
 127 void *dm_rh_region_context(struct dm_region *reg)
 128 {
 129         return reg->rh->context;
 130 }
 131 EXPORT_SYMBOL_GPL(dm_rh_region_context);
 132
 133 region_t dm_rh_get_region_key(struct dm_region *reg)
 134 {
 135         return reg->key;
 136 }
 137 EXPORT_SYMBOL_GPL(dm_rh_get_region_key);
 138
 139 sector_t dm_rh_get_region_size(struct dm_region_hash *rh)
 140 {
 141         return rh->region_size;
 142 }
 143 EXPORT_SYMBOL_GPL(dm_rh_get_region_size);
 144
 145 /*
 146  * FIXME: shall we pass in a structure instead of all these args to
 147  * dm_region_hash_create()????
 148  */
 149 #define RH_HASH_MULT 2654435387U
 150 #define RH_HASH_SHIFT 12
 151
 152 #define MIN_REGIONS 64
 153 struct dm_region_hash *dm_region_hash_create(
 154                 void *context, void (*dispatch_bios)(void *context,
 155                                                      struct bio_list *bios),
 156                 void (*wakeup_workers)(void *context),
 157                 void (*wakeup_all_recovery_waiters)(void *context),
 158                 sector_t target_begin, unsigned max_recovery,
 159                 struct dm_dirty_log *log, uint32_t region_size,
 160                 region_t nr_regions)
 161 {
 162         struct dm_region_hash *rh;
 163         unsigned nr_buckets, max_buckets;
 164         size_t i;
 165
 166         /*
 167          * Calculate a suitable number of buckets for our hash
 168          * table.
 169          */
 170         max_buckets = nr_regions >> 6;
 171         for (nr_buckets = 128u; nr_buckets < max_buckets; nr_buckets <<= 1)
 172                 ;
 173         nr_buckets >>= 1;
 174
 175         rh = kmalloc(sizeof(*rh), GFP_KERNEL);
 176         if (!rh) {
 177                 DMERR("unable to allocate region hash memory");
 178                 return ERR_PTR(-ENOMEM);
 179         }
 180
 181         rh->context = context;
 182         rh->dispatch_bios = dispatch_bios;
 183         rh->wakeup_workers = wakeup_workers;
 184         rh->wakeup_all_recovery_waiters = wakeup_all_recovery_waiters;
 185         rh->target_begin = target_begin;
 186         rh->max_recovery = max_recovery;
 187         rh->log = log;
 188         rh->region_size = region_size;
 189         rh->region_shift = ffs(region_size) - 1;
 190         rwlock_init(&rh->hash_lock);
 191         rh->mask = nr_buckets - 1;
 192         rh->nr_buckets = nr_buckets;
 193
 194         rh->shift = RH_HASH_SHIFT;
 195         rh->prime = RH_HASH_MULT;
 196
 197         rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets));
 198         if (!rh->buckets) {
 199                 DMERR("unable to allocate region hash bucket memory");
 200                 kfree(rh);
 201                 return ERR_PTR(-ENOMEM);
 202         }
 203
 204         for (i = 0; i < nr_buckets; i++)
 205                 INIT_LIST_HEAD(rh->buckets + i);
 206
 207         spin_lock_init(&rh->region_lock);
 208         sema_init(&rh->recovery_count, 0);
 209         atomic_set(&rh->recovery_in_flight, 0);
 210         INIT_LIST_HEAD(&rh->clean_regions);
 211         INIT_LIST_HEAD(&rh->quiesced_regions);
 212         INIT_LIST_HEAD(&rh->recovered_regions);
 213         INIT_LIST_HEAD(&rh->failed_recovered_regions);
 214
 215         rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS,
 216                                                       sizeof(struct dm_region));
 217         if (!rh->region_pool) {
 218                 vfree(rh->buckets);
 219                 kfree(rh);
 220                 rh = ERR_PTR(-ENOMEM);
 221         }
 222
 223         return rh;
 224 }
 225 EXPORT_SYMBOL_GPL(dm_region_hash_create);
 226
 227 void dm_region_hash_destroy(struct dm_region_hash *rh)
 228 {
 229         unsigned h;
 230         struct dm_region *reg, *nreg;
 231
 232         BUG_ON(!list_empty(&rh->quiesced_regions));
 233         for (h = 0; h < rh->nr_buckets; h++) {
 234                 list_for_each_entry_safe(reg, nreg, rh->buckets + h,
 235                                          hash_list) {
 236                         BUG_ON(atomic_read(&reg->pending));
 237                         mempool_free(reg, rh->region_pool);
 238                 }
 239         }
 240
 241         if (rh->log)
 242                 dm_dirty_log_destroy(rh->log);
 243
 244         if (rh->region_pool)
 245                 mempool_destroy(rh->region_pool);
 246
 247         vfree(rh->buckets);
 248         kfree(rh);
 249 }
 250 EXPORT_SYMBOL_GPL(dm_region_hash_destroy);
 251
 252 struct dm_dirty_log *dm_rh_dirty_log(struct dm_region_hash *rh)
 253 {
 254         return rh->log;
 255 }
 256 EXPORT_SYMBOL_GPL(dm_rh_dirty_log);
 257
 258 static unsigned rh_hash(struct dm_region_hash *rh, region_t region)
 259 {
 260         return (unsigned) ((region * rh->prime) >> rh->shift) & rh->mask;
 261 }
 262
 263 static struct dm_region *__rh_lookup(struct dm_region_hash *rh, region_t region)
 264 {
 265         struct dm_region *reg;
 266         struct list_head *bucket = rh->buckets + rh_hash(rh, region);
 267
 268         list_for_each_entry(reg, bucket, hash_list)
 269                 if (reg->key == region)
 270                         return reg;
 271
 272         return NULL;
 273 }
 274
 275 static void __rh_insert(struct dm_region_hash *rh, struct dm_region *reg)
 276 {
 277         list_add(&reg->hash_list, rh->buckets + rh_hash(rh, reg->key));
 278 }
 279
 280 static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
 281 {
 282         struct dm_region *reg, *nreg;
 283
 284         nreg = mempool_alloc(rh->region_pool, GFP_ATOMIC);
 285         if (unlikely(!nreg))
 286                 nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
 287
 288         nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
 289                       DM_RH_CLEAN : DM_RH_NOSYNC;
 290         nreg->rh = rh;
 291         nreg->key = region;
 292         INIT_LIST_HEAD(&nreg->list);
 293         atomic_set(&nreg->pending, 0);
 294         bio_list_init(&nreg->delayed_bios);
 295
 296         write_lock_irq(&rh->hash_lock);
 297         reg = __rh_lookup(rh, region);
 298         if (reg)
 299                 /* We lost the race. */
 300                 mempool_free(nreg, rh->region_pool);
 301         else {
 302                 __rh_insert(rh, nreg);
 303                 if (nreg->state == DM_RH_CLEAN) {
 304                         spin_lock(&rh->region_lock);
 305                         list_add(&nreg->list, &rh->clean_regions);
 306                         spin_unlock(&rh->region_lock);
 307                 }
 308
 309                 reg = nreg;
 310         }
 311         write_unlock_irq(&rh->hash_lock);
 312
 313         return reg;
 314 }
 315
 316 static struct dm_region *__rh_find(struct dm_region_hash *rh, region_t region)
 317 {
 318         struct dm_region *reg;
 319
 320         reg = __rh_lookup(rh, region);
 321         if (!reg) {
 322                 read_unlock(&rh->hash_lock);
 323                 reg = __rh_alloc(rh, region);
 324                 read_lock(&rh->hash_lock);
 325         }
 326
 327         return reg;
 328 }
 329
 330 int dm_rh_get_state(struct dm_region_hash *rh, region_t region, int may_block)
 331 {
 332         int r;
 333         struct dm_region *reg;
 334
 335         read_lock(&rh->hash_lock);
 336         reg = __rh_lookup(rh, region);
 337         read_unlock(&rh->hash_lock);
 338
 339         if (reg)
 340                 return reg->state;
 341
 342         /*
 343          * The region wasn't in the hash, so we fall back to the
 344          * dirty log.
 345          */
 346         r = rh->log->type->in_sync(rh->log, region, may_block);
 347
 348         /*
 349          * Any error from the dirty log (eg. -EWOULDBLOCK) gets
 350          * taken as a DM_RH_NOSYNC
 351          */
 352         return r == 1 ? DM_RH_CLEAN : DM_RH_NOSYNC;
 353 }
 354 EXPORT_SYMBOL_GPL(dm_rh_get_state);
 355
 356 static void complete_resync_work(struct dm_region *reg, int success)
 357 {
 358         struct dm_region_hash *rh = reg->rh;
 359
 360         rh->log->type->set_region_sync(rh->log, reg->key, success);
 361
 362         /*
 363          * Dispatch the bios before we call 'wake_up_all'.
 364          * This is important because if we are suspending,
 365          * we want to know that recovery is complete and
 366          * the work queue is flushed.  If we wake_up_all
 367          * before we dispatch_bios (queue bios and call wake()),
 368          * then we risk suspending before the work queue
 369          * has been properly flushed.
 370          */
 371         rh->dispatch_bios(rh->context, &reg->delayed_bios);
 372         if (atomic_dec_and_test(&rh->recovery_in_flight))
 373                 rh->wakeup_all_recovery_waiters(rh->context);
 374         up(&rh->recovery_count);
 375 }
 376
 377 /* dm_rh_mark_nosync
 378  * @ms
 379  * @bio
 380  * @done
 381  * @error
 382  *
 383  * The bio was written on some mirror(s) but failed on other mirror(s).
 384  * We can successfully endio the bio but should avoid the region being
 385  * marked clean by setting the state DM_RH_NOSYNC.
 386  *
 387  * This function is _not_ safe in interrupt context!
 388  */
 389 void dm_rh_mark_nosync(struct dm_region_hash *rh,
 390                        struct bio *bio, unsigned done, int error)
 391 {
 392         unsigned long flags;
 393         struct dm_dirty_log *log = rh->log;
 394         struct dm_region *reg;
 395         region_t region = dm_rh_bio_to_region(rh, bio);
 396         int recovering = 0;
 397
 398         /* We must inform the log that the sync count has changed. */
 399         log->type->set_region_sync(log, region, 0);
 400
 401         read_lock(&rh->hash_lock);
 402         reg = __rh_find(rh, region);
 403         read_unlock(&rh->hash_lock);
 404
 405         /* region hash entry should exist because write was in-flight */
 406         BUG_ON(!reg);
 407         BUG_ON(!list_empty(&reg->list));
 408
 409         spin_lock_irqsave(&rh->region_lock, flags);
 410         /*
 411          * Possible cases:
 412          *   1) DM_RH_DIRTY
 413          *   2) DM_RH_NOSYNC: was dirty, other preceeding writes failed
 414          *   3) DM_RH_RECOVERING: flushing pending writes
 415          * Either case, the region should have not been connected to list.
 416          */
 417         recovering = (reg->state == DM_RH_RECOVERING);
 418         reg->state = DM_RH_NOSYNC;
 419         BUG_ON(!list_empty(&reg->list));
 420         spin_unlock_irqrestore(&rh->region_lock, flags);
 421
 422         bio_endio(bio, error);
 423         if (recovering)
 424                 complete_resync_work(reg, 0);
 425 }
 426 EXPORT_SYMBOL_GPL(dm_rh_mark_nosync);
 427
 428 void dm_rh_update_states(struct dm_region_hash *rh, int errors_handled)
 429 {
 430         struct dm_region *reg, *next;
 431
 432         LIST_HEAD(clean);
 433         LIST_HEAD(recovered);
 434         LIST_HEAD(failed_recovered);
 435
 436         /*
 437          * Quickly grab the lists.
 438          */
 439         write_lock_irq(&rh->hash_lock);
 440         spin_lock(&rh->region_lock);
 441         if (!list_empty(&rh->clean_regions)) {
 442                 list_splice_init(&rh->clean_regions, &clean);
 443
 444                 list_for_each_entry(reg, &clean, list)
 445                         list_del(&reg->hash_list);
 446         }
 447
 448         if (!list_empty(&rh->recovered_regions)) {
 449                 list_splice_init(&rh->recovered_regions, &recovered);
 450
 451                 list_for_each_entry(reg, &recovered, list)
 452                         list_del(&reg->hash_list);
 453         }
 454
 455         if (!list_empty(&rh->failed_recovered_regions)) {
 456                 list_splice_init(&rh->failed_recovered_regions,
 457                                  &failed_recovered);
 458
 459                 list_for_each_entry(reg, &failed_recovered, list)
 460                         list_del(&reg->hash_list);
 461         }
 462
 463         spin_unlock(&rh->region_lock);
 464         write_unlock_irq(&rh->hash_lock);
 465
 466         /*
 467          * All the regions on the recovered and clean lists have
 468          * now been pulled out of the system, so no need to do
 469          * any more locking.
 470          */
 471         list_for_each_entry_safe(reg, next, &recovered, list) {
 472                 rh->log->type->clear_region(rh->log, reg->key);
 473                 complete_resync_work(reg, 1);
 474                 mempool_free(reg, rh->region_pool);
 475         }
 476
 477         list_for_each_entry_safe(reg, next, &failed_recovered, list) {
 478                 complete_resync_work(reg, errors_handled ? 0 : 1);
 479                 mempool_free(reg, rh->region_pool);
 480         }
 481
 482         list_for_each_entry_safe(reg, next, &clean, list) {
 483                 rh->log->type->clear_region(rh->log, reg->key);
 484                 mempool_free(reg, rh->region_pool);
 485         }
 486
 487         rh->log->type->flush(rh->log);
 488 }
 489 EXPORT_SYMBOL_GPL(dm_rh_update_states);
 490
 491 static void rh_inc(struct dm_region_hash *rh, region_t region)
 492 {
 493         struct dm_region *reg;
 494
 495         read_lock(&rh->hash_lock);
 496         reg = __rh_find(rh, region);
 497
 498         spin_lock_irq(&rh->region_lock);
 499         atomic_inc(&reg->pending);
 500
 501         if (reg->state == DM_RH_CLEAN) {
 502                 reg->state = DM_RH_DIRTY;
 503                 list_del_init(&reg->list);      /* take off the clean list */
 504                 spin_unlock_irq(&rh->region_lock);
 505
 506                 rh->log->type->mark_region(rh->log, reg->key);
 507         } else
 508                 spin_unlock_irq(&rh->region_lock);
 509
 510
 511         read_unlock(&rh->hash_lock);
 512 }
 513
 514 void dm_rh_inc_pending(struct dm_region_hash *rh, struct bio_list *bios)
 515 {
 516         struct bio *bio;
 517
 518         for (bio = bios->head; bio; bio = bio->bi_next)
 519                 rh_inc(rh, dm_rh_bio_to_region(rh, bio));
 520 }
 521 EXPORT_SYMBOL_GPL(dm_rh_inc_pending);
 522
 523 void dm_rh_dec(struct dm_region_hash *rh, region_t region)
 524 {
 525         unsigned long flags;
 526         struct dm_region *reg;
 527         int should_wake = 0;
 528
 529         read_lock(&rh->hash_lock);
 530         reg = __rh_lookup(rh, region);
 531         read_unlock(&rh->hash_lock);
 532
 533         spin_lock_irqsave(&rh->region_lock, flags);
 534         if (atomic_dec_and_test(&reg->pending)) {
 535                 /*
 536                  * There is no pending I/O for this region.
 537                  * We can move the region to corresponding list for next action.
 538                  * At this point, the region is not yet connected to any list.
 539                  *
 540                  * If the state is DM_RH_NOSYNC, the region should be kept off
 541                  * from clean list.
 542                  * The hash entry for DM_RH_NOSYNC will remain in memory
 543                  * until the region is recovered or the map is reloaded.
 544                  */
 545
 546                 /* do nothing for DM_RH_NOSYNC */
 547                 if (reg->state == DM_RH_RECOVERING) {
 548                         list_add_tail(&reg->list, &rh->quiesced_regions);
 549                 } else if (reg->state == DM_RH_DIRTY) {
 550                         reg->state = DM_RH_CLEAN;
 551                         list_add(&reg->list, &rh->clean_regions);
 552                 }
 553                 should_wake = 1;
 554         }
 555         spin_unlock_irqrestore(&rh->region_lock, flags);
 556
 557         if (should_wake)
 558                 rh->wakeup_workers(rh->context);
 559 }
 560 EXPORT_SYMBOL_GPL(dm_rh_dec);
 561
 562 /*
 563  * Starts quiescing a region in preparation for recovery.
 564  */
 565 static int __rh_recovery_prepare(struct dm_region_hash *rh)
 566 {
 567         int r;
 568         region_t region;
 569         struct dm_region *reg;
 570
 571         /*
 572          * Ask the dirty log what's next.
 573          */
 574         r = rh->log->type->get_resync_work(rh->log, &region);
 575         if (r <= 0)
 576                 return r;
 577
 578         /*
 579          * Get this region, and start it quiescing by setting the
 580          * recovering flag.
 581          */
 582         read_lock(&rh->hash_lock);
 583         reg = __rh_find(rh, region);
 584         read_unlock(&rh->hash_lock);
 585
 586         spin_lock_irq(&rh->region_lock);
 587         reg->state = DM_RH_RECOVERING;
 588
 589         /* Already quiesced ? */
 590         if (atomic_read(&reg->pending))
 591                 list_del_init(&reg->list);
 592         else
 593                 list_move(&reg->list, &rh->quiesced_regions);
 594
 595         spin_unlock_irq(&rh->region_lock);
 596
 597         return 1;
 598 }
 599
 600 void dm_rh_recovery_prepare(struct dm_region_hash *rh)
 601 {
 602         /* Extra reference to avoid race with dm_rh_stop_recovery */
 603         atomic_inc(&rh->recovery_in_flight);
 604
 605         while (!down_trylock(&rh->recovery_count)) {
 606                 atomic_inc(&rh->recovery_in_flight);
 607                 if (__rh_recovery_prepare(rh) <= 0) {
 608                         atomic_dec(&rh->recovery_in_flight);
 609                         up(&rh->recovery_count);
 610                         break;
 611                 }
 612         }
 613
 614         /* Drop the extra reference */
 615         if (atomic_dec_and_test(&rh->recovery_in_flight))
 616                 rh->wakeup_all_recovery_waiters(rh->context);
 617 }
 618 EXPORT_SYMBOL_GPL(dm_rh_recovery_prepare);
 619
 620 /*
 621  * Returns any quiesced regions.
 622  */
 623 struct dm_region *dm_rh_recovery_start(struct dm_region_hash *rh)
 624 {
 625         struct dm_region *reg = NULL;
 626
 627         spin_lock_irq(&rh->region_lock);
 628         if (!list_empty(&rh->quiesced_regions)) {
 629                 reg = list_entry(rh->quiesced_regions.next,
 630                                  struct dm_region, list);
 631                 list_del_init(&reg->list);  /* remove from the quiesced list */
 632         }
 633         spin_unlock_irq(&rh->region_lock);
 634
 635         return reg;
 636 }
 637 EXPORT_SYMBOL_GPL(dm_rh_recovery_start);
 638
 639 void dm_rh_recovery_end(struct dm_region *reg, int success)
 640 {
 641         struct dm_region_hash *rh = reg->rh;
 642
 643         spin_lock_irq(&rh->region_lock);
 644         if (success)
 645                 list_add(&reg->list, &reg->rh->recovered_regions);
 646         else {
 647                 reg->state = DM_RH_NOSYNC;
 648                 list_add(&reg->list, &reg->rh->failed_recovered_regions);
 649         }
 650         spin_unlock_irq(&rh->region_lock);
 651
 652         rh->wakeup_workers(rh->context);
 653 }
 654 EXPORT_SYMBOL_GPL(dm_rh_recovery_end);
 655
 656 /* Return recovery in flight count. */
 657 int dm_rh_recovery_in_flight(struct dm_region_hash *rh)
 658 {
 659         return atomic_read(&rh->recovery_in_flight);
 660 }
 661 EXPORT_SYMBOL_GPL(dm_rh_recovery_in_flight);
 662
 663 int dm_rh_flush(struct dm_region_hash *rh)
 664 {
 665         return rh->log->type->flush(rh->log);
 666 }
 667 EXPORT_SYMBOL_GPL(dm_rh_flush);
 668
 669 void dm_rh_delay(struct dm_region_hash *rh, struct bio *bio)
 670 {
 671         struct dm_region *reg;
 672
 673         read_lock(&rh->hash_lock);
 674         reg = __rh_find(rh, dm_rh_bio_to_region(rh, bio));
 675         bio_list_add(&reg->delayed_bios, bio);
 676         read_unlock(&rh->hash_lock);
 677 }
 678 EXPORT_SYMBOL_GPL(dm_rh_delay);
 679
 680 void dm_rh_stop_recovery(struct dm_region_hash *rh)
 681 {
 682         int i;
 683
 684         /* wait for any recovering regions */
 685         for (i = 0; i < rh->max_recovery; i++)
 686                 down(&rh->recovery_count);
 687 }
 688 EXPORT_SYMBOL_GPL(dm_rh_stop_recovery);
 689
 690 void dm_rh_start_recovery(struct dm_region_hash *rh)
 691 {
 692         int i;
 693
 694         for (i = 0; i < rh->max_recovery; i++)
 695                 up(&rh->recovery_count);
 696
 697         rh->wakeup_workers(rh->context);
 698 }
 699 EXPORT_SYMBOL_GPL(dm_rh_start_recovery);
 700
 701 MODULE_DESCRIPTION(DM_NAME " region hash");
 702 MODULE_AUTHOR("Joe Thornber/Heinz Mauelshagen <dm-devel@redhat.com>");
 703 MODULE_LICENSE("GPL");